Why MP4 won’t play on Windows and how to fix it

MP4 file won’t play? An incredibly common problem, which, fortunately, is “treated” extremely simply.

A huge number of people on the net complain that MP4 files are not played on their computer (or are played, but incorrectly, for example, with delays, brakes). As a rule, such a problem occurs immediately after installing a clean Windows, but it also happens that people also encounter a problem on “traveled” systems.

In today’s article, we will tell you why MP4 files won’t open and how you can fix it.


  • Why MP4 won’t play? Possible reasons
  • What to do if MP4 won’t play
    • #1 Checking the file
    • #2 Installing a set of codecs
    • No. 3 Recreating the playlist, resetting the settings, reinstalling the media player

Why MP4 won’t play? Possible reasons

  • Unsupported video format: The media player you are using simply does not support the file format. In addition, if the file extension indicates “MP4”, then this does not mean that this is really a file of this format. It may not be a media file at all.
  • The system does not have the necessary set of codecs:  The user will not be able to open video files in MP4 format if his system does not have the appropriate set of codecs (special tools, libraries, whose task is to encode / decode multimedia information).
  • The location of the MP4 file is incorrect or not available:  The video player may have difficulty playing an MP4 file if the location of the latter is incorrect or not available to the player.
  • Incorrect video player settings: By changing some of the video player settings, the user may be unable to play certain video file formats, including MP4. Changing the settings can also occur when installing a fresh update for the video player.
  • The files of the player being used are corrupted: The user can open video files normally if some of the files of the media player itself have been corrupted. It should be noted that such a situation occurs extremely rarely, but it is still possible, for example, when updating the player or when moving its files to another directory.

What to do if MP4 won’t play

#1 Checking the file

The MP4 file you are trying to play may be damaged or modified in such a way that your player cannot work with it. Try opening another file with the same extension and see if the situation repeats. There is a chance that the file extension has been changed and it is not MP4, but BIK, 3GP, or even not a media file at all.

If other MP4 files do not open, then the problem is probably in the media player itself or the system lacks the necessary codecs. About all this – below.

#2 Installing a set of codecs

Modern players support most media formats, however, in some cases, an additional set of codecs is required. There are many universal kits on the Internet, but we recommend that you pay attention to the K-Lite Codec Pack .

The set is installed in a semi-automatic mode – you should not have any problems. If you are not sure about the choice of parameters (or do not know English), then just click several times on “Next”, and at the end – on “Install”. MPC (Media Player Classic) and a set of codecs for it will be installed on your PC.

No. 3 Recreating the playlist, resetting the settings, reinstalling the media player

Trying to play an MP4 file from a previously created playlist, but the player refuses to do so? Well, there could be several reasons for this:

  • moving a file to another directory;
  • changing the symbols of the directory itself, for example, replacing Latin with Cyrillic and vice versa;
  • deleting a file from the directory where it was previously located.

Go to the location of the file and open it manually (if it’s still there, of course). File opened? Then add it to your playlist. If that doesn’t work, create a new playlist with the file. Well, the file is in place, opened manually, the directory has not changed, but it is not played in the playlist – what should I do? Reset your media player or reinstall it. Are you using pre-installed Windows media? We recommend installing a third-party player, such as MPC or VLC.

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